1. Field of the Invention
The present invention relates to a solid-state imaging device in which first and second substrates provided with circuit elements constituting each pixel are electrically connected.
Priority is claimed on Japanese Patent Application No. 2012-065461, filed Mar. 22, 2012, the content of which is incorporated herein by reference.
2. Description of Related Art
In recent years, video cameras, electronic still cameras, and the like have been proliferated generally and widely. In such cameras, charge coupled device (CCD) type or amplification type solid-state imaging devices have been used. In the amplification type solid-state imaging device, a signal charge generated and accumulated by a photoelectric conversion unit of each pixel on which light is incident is guided to an amplification unit installed in the pixel, and then a signal amplified by the amplification unit is output from the pixel. In the amplification type solid-state imaging device, the plurality of pixels are arrayed in a two-dimensional matrix form. An example of the amplification type solid-state imaging device includes a complementary metal oxide semiconductor (CMOS) type solid-state imaging device using a CMOS transistor.
According to the related art, a general CMOS type solid-state imaging device adopts a method of sequentially reading signal charges generated by the photoelectric conversion units of the respective pixels arrayed in the two-dimensional matrix form for each row. In this method, exposure timing is different for each row, since the exposure timing in the photoelectric conversion unit of each pixel is determined by a beginning and end of reading of the signal charges.
Further, the CMOS type solid-state imaging device having a global shutter function has been applied for many uses. The CMOS type solid-state imaging device having the global shutter function is generally required to include an accumulation capacitor unit having a light shielding property in order to store the signal charge generated by the photoelectric conversion unit until the signal charge is read. In the CMOS type solid-state imaging device according to the related art, after all of the pixels are simultaneously exposed, the signal charges generated by the respective photoelectric conversion units are simultaneously transmitted to the accumulation capacitor units and are temporarily accumulated in all of the pixels. Then, the signal charges are sequentially converted into pixel signals at predetermined reading timings to be read.
Japanese Unexamined Patent Application, First Publication No. 2006-49361 discloses a solid-state imaging device configured such that a MOS image sensor chip in which a micropad is formed for each unit cell on a wiring layer side and a signal processing chip in which a micropad is formed on the wiring layer side at a position corresponding to the micropad of the MOS image sensor chip are connected by a microbump. Further, Japanese Unexamined Patent Application, First Publication No. 2010-219339 discloses a method of suppressing an increase in a chip area in a solid-state imaging device in which a first substrate provided with photoelectric conversion units and a second substrate provided with a plurality of MOS transistors are bonded.